Methods for regulating the flow of blood through the blood system

ABSTRACT

A valve prosthesis is disclosed which is implantable within a vein or other blood vessel of a patient using a minimally-invasive surgical procedure. The prosthesis includes a tubular wire frame which presses radially outward against the inner walls of the blood vessel following implantation to hold the prosthesis in position. Multiple flow-resistive pockets that open and close in response to changes in blood flow direction are attached to the frame to impede the flow of blood in the reverse direction. The prosthesis is implanted using an introducer catheter which holds the prosthesis in a radially-compressed state as the prosthesis is inserted into and positioned within the blood vessel.

[0001] This application is a continuation of U.S. application Ser. No.09/630,403, filed Aug. 1, 2000, which is a continuation of U.S.application Ser. No. 08/992,350 (issued as U.S. Pat. No. 6,287,334),filed on Dec. 17, 1997, which claims priority from NetherlandsApplication No. 1004827, filed Dec. 18, 1996, each of the aforementionedapplications being incorporated by reference in their entirety.

[0002] The present invention relates to a device for regulating the flowof blood in blood vessels.

[0003] The blood system, and in particular the venal blood system of thelegs and arms are provided with valves, at predetermined positions,which ensure that blood cannot flow back along the system in thedirection from which it has just been pumped, to only be displaced inthe direction of the heart.

[0004] In the arms and legs, there is a deep and a surface venal system.

[0005] Due to various causes, thrombosis can occur in especially thedeep venal system. Following thinning of the blood, passage of the bloodthrough the system is often again possible, but in this case the valvesdo not effectively close off the system and often leak. This causes anincreased venal blood pressure in the direction of the ankles, whichleads to many problems, such as varicose veins and the infamous “openleg”. This type of complaint is wide spread among people who spend avast majority of their working hours in a standing position, forinstance surgeons.

[0006] The surface venal system of the leg is weaker than the deepsystem, and has the tendency to spontaneously widen, whereby the valvesno longer function effectively, leading to varicose veins, which, apartfrom being highly unattractive, are also very painful. Major surgery isoften required to deal with these blood vessel valve problems.

[0007] For example varicose veins are presently surgically operated on,by either closing off the vein, which leads to a reduced blood flowcapacity and extra pressure on surrounding blood vessels in order toensure blood supply, or by completely removing the varicose veins, whichleads to the same problem.

[0008] An object of the present invention is to obviate one or more ofthese problems.

[0009] According to a first aspect, the present invention provides adevice for regulating the flow of blood in blood vessels, comprising oneor more flow stoppage elements, each comprising:

[0010] a flareable proximal end, flareable between a flared, flowstoppage configuration and a substantially flattened, flow permittingconfiguration, and

[0011] a middle section extending from the proximal end to terminate ina distal end.

[0012] By introducing a synthetic device which acts as a valve, theblood flow is now able to be regulated in substantially the normalmanner.

[0013] The device preferably further comprises:

[0014] an opening associated with the proximal end, the middle sectioncomprising one or more sidewalls extending from this proximal endopening to join together at the distal end, the sidewalls beingdisplaceable, by the flow of blood through the device between the flaredconfiguration, wherein the element encloses a temporary blood storagearea, and the substantially flattened configuration wherein the one ormore sidewalls lie substantially flat adjacent to each other.

[0015] When occupying the blood flow stoppage configuration, the flowstoppage element encloses a temporary blood storage area between itsopen proximal end and the closed distal end. In this way betweenheartbeats, which force the blood through the venal system, any bloodflowing in the opposite direction to the blood stream opens the proximalend of the stoppage element thereby forcing the sidewalls apart to enterthe temporary blood storage area, instead of passing through the deviceto leak back into the blood vessel in the direction from where it hasjust been pumped. Since opening of the blood flow stoppage elementeffectively closes off the blood vessel, a very effective valve isprovided.

[0016] The flow stoppage element is preferably mounted on a supporthaving such a form as to pass within a blood vessel. This provides extrastability.

[0017] Further, the support frame comprises a resilient wire and isbiased toward an unrolled configuration.

[0018] The stoppage element is preferably substantially conical in shapewhen occupying the blood flow stoppage configuration, the closed distalend being synonymous with the tip of the cone and the proximal endopening being synonymous with the flared base of the cone. This yields ahighly effective valve working.

[0019] The support is preferably adjustable between an introducing form,wherein the device is suitable for introducing into a blood vessel, andan expanded form suitable for supporting the stoppage element within ablood vessel at the desired working location thereof, and mostpreferably has such a form as to have substantially the same length whenoccupying its introducing form as when occupying its expanded form.Accordingly the device can be effectively introduced to a pre-desiredlocation within a blood vessel, whereafter it is expandable to take upits working form. Since the support has substantially the same lengthwhen in its introducing form as in its expanded form, the stoppageelements remain effectively supported, and any damage ensuing fromalteration of the length of the support within the blood system iseffectively obviated.

[0020] In order to yield a very effective valve working, the supportpreferably comprises substantially separate frame sections for each ofthe one or more fluid passage stoppage elements.

[0021] According to another aspect of the present invention, there isprovided a support for a fluid stoppage element as referred to above.

[0022] According to yet a further aspect of the present invention thereis provided a method for regulating the flow of blood in the bloodstream comprising introducing the above device into a blood vessel, sothat the distal end thereof is arranged downstream from the proximalend, wherein the proximal end opening is closed by the pressure of bloodflowing through the device, as blood is pumped through the system by theheart, wherein blood flowing in the opposite direction to which it ispumped between beats, flows into the proximal end of the device, whichis subsequently thereby opened to force the sidewalls of the deviceagainst the blood vessel walls, thereby closing off the passage of bloodin the blood vessel, wherein blood is trapped in the temporary bloodstorage area enclosed by the sidewalls of the device before a subsequentvolume of blood being pumped through the device claps said sidewallsshut, thereby expelling blood out of the temporary storage area andfurther through the system.

[0023] The introducer preferably comprises an elongated sliding memberwhich is advanceable by a physician to forcibly displace the valveprosthesis from the hollow distal portion of said introducer into theblood vessel.

[0024] The present invention will now be further clarified by way of thefollowing specific description, which refers to FIGS. 1 to 7, wherein:

[0025]FIG. 1 is a perspective view of the device according to thepresent invention;

[0026]FIG. 2 is a side view of a support for a flow stoppage elementaccording to the present invention,

[0027]FIG. 3 is a perspective view of the device from FIG. 1, whenoccupying its introducing form, as to be introducible into a bloodvessel;

[0028]FIG. 4 is a perspective view showing the introduction of a deviceas shown in FIG. 1 into a blood vessel;

[0029]FIG. 5 is a perspective view as in FIG. 4, showing the device whenoccupying its blood flow through put position;

[0030]FIG. 6 shows the device from FIG. 1, with the support (not shown)in order to provide maximum clarity, when occupying its blood flowstoppage position within a blood vessel; and

[0031]FIG. 7 is a perspective view of two devices as shown in FIG. 1,when placed in a vein in the leg.

[0032] A device 1 (FIG. 1) according to the present invention has aproximal end 2 and a distal end 4.

[0033] Blood flow stoppage elements 6, having the form of flexiblehollow cones, are each supported on a substantially triangular framesection 8 of a support 10, see also FIG. 2.

[0034] The valve elements 6 have an inner wall 12 and an outer wall 14extending from a proximal end (2) opening 16 in the “flared”configuration to join together and terminate in the form of a pointedend section 17 at the distal end 4.

[0035] The support 10 is preferably made of a continuous length ofmemory metal, having, as shown in FIGS. 1 and 2, three substantiallyseparate frame sections 8 for supporting each valve element 6.

[0036] As shown in FIG. 3, the frame 10 can be rolled up so that framesections 8 partially overlap one another.

[0037] In such a position the device 1 is easily introduced into a bloodvessel.

[0038] On being placed at its desired position within the blood system,the device, once the memory metal has achieved a particularpredetermined temperature, will expand in order to assume its workingform as shown in FIG. 1, whereby since in its introducing form (FIG. 3),an area of overlap exists between the terminal frame sections 8, thedevice 1 remains substantially the same length in its working position(FIG. 1) as in it introducing position (FIG. 3).

[0039] In order to ensure biocompatibility, the support and bloodstoppage elements are made of biocompatible material, whereby the bloodstoppage elements are most preferably made of polytetrafluoroethylene(PTFE).

[0040] The device 1 is folded up into its introducing form, as shown inFIG. 3, whereafter once arranged in an introducing device 18, as shownin FIGS. 3 and 4, the device 1 is introducible into a blood vessel 20 asshown in FIG. 4.

[0041] On assuming its working configuration as shown in FIGS. 1, 5, 6and 7, the blood is regulated in the blood vessel by the device asfollows.

[0042] Blood is pumped through the blood vessel 20 (FIG. 5) and throughthe device 1 (FIG. 5) on the beat of the heart. This means that insteadof flowing at a constant rate through the blood vessel, that blood flowsthrough the blood system, in particular through veins, as a series ofpulses. Between each pulse, the blood is not being actively forcedthrough the system and can flow back from where it came.

[0043] When actively pumped through the system, blood is forced throughthe device 1 through the distal end 4 and out of the proximal end 2(FIG. 5).

[0044] In this position (FIG. 5), the flow of the blood through thedevice 1, forces the inner walls 12 of the stoppage elements 6 againstthe outer walls 14 thereof in order to effect a blood flow throughchannel.

[0045] Between heartbeats, blood having just passed through the proximalopening 2 of the device 1, can flow back down the blood vessel 20. Ondoing so, it forces the inner walls 12 away from the outer walls 14 ofthese elements 6 at the proximal end 2 of the device 1 to create theopening 16 leading into a temporary blood storage area 22. Since theinner walls 12 and the outer walls 14 are joined together at the distalend 4 of the device, the temporary blood storage area 22 is effected ineach blood stoppage element 6 at this phase (FIG. 6).

[0046] During the next pulse of blood through the device 1 from thedistal end 4, the inner walls 12 are forced against the outer walls 14of the stoppage elements 6, thus forcing the blood temporarily storedtherein out of the blood stoppage elements 6 and effecting the openchannel to enable blood through flow.

What is claimed is:
 1. A minimally-invasive method of implanting a valveprosthesis device within an existing vein of a human to restore venousvalvular function within the vein, the valve prosthesis device adaptedto press outward against the inner walls of the vein to hold the valveprosthesis device in position within the vein following implantation,the method comprising the steps of: positioning the valve prosthesisdevice within a hollow distal portion of an introducer with the valveprosthesis device in a compressed state; advancing the hollow distalportion of the introducer, with the valve prosthesis device positionedtherein, into the vein of the human through an opening in a wall of thevein; and expelling the valve prosthesis device from the distal portioninto the vein to cause the device to expand to an operational state inwhich the valve prosthesis device is maintained in position within thevein by pressing outward against the inner walls of the vein.
 2. Themethod of claim 1, wherein the step of expelling comprises slidablyadvancing an expulsion member distally to forcibly displace the valveprosthesis device from the distal portion of the introducer.
 3. Themethod of claim 1, wherein the valve prosthesis device comprises agenerally flat, resilient frame which is rollable upon itself to placethe frame in a tubular configuration, and wherein the step ofpositioning comprises rolling the frame against a biasing force to placethe valve prosthesis device in a radially-compressed configuration thatcorresponds to an inner diameter of the hollow distal portion of theintroducer.
 4. A method for regulating the flow of blood in a bloodvessel through an implantable venous valve prosthesis device having aproximal end and a distal end, the method comprising: directing a pulseof blood through the distal end of the prosthesis device and out theproximal end; opening a temporary blood storage area having inner andouter walls within the prosthesis device to prevent the pulse of bloodfrom flowing back through the distal end of the device; and storing anyback-flowing blood within the temporary blood storage area between theinner and outer walls.
 5. The method of claim 4, further comprisingclosing the temporary blood storage area and forcing the blood storedtherein out of the storage area and out of the proximal end of thedevice upon the passage of a subsequent pulse of blood through thedistal end of the prosthesis device and out the proximal end.
 6. Themethod of claim 4, wherein the temporary blood storage area comprises atleast one pocket having an opening adjacent the proximal end of thedevice.
 7. The method of claim 6, wherein the temporary blood storagearea comprises three pockets arranged substantially circumferentiallywithin the device.
 8. The method of claim 7, wherein directing the pulseof blood through the device comprises directing the pulse of bloodbetween the pockets.